Sodium borocaptate (BSH, Na2Bi2HnSH), a slow neutron-capture compound, was injected into the left forebrain ventricle of 1-week-old rats (150 fig BSH/3 p\ phosphate buffered saline). After 90 min, the animals were irradiated by epithermal neutrons (LVR-15 nuclear reactor in Řež near Prague, flux density 8.8 x 107 neutrons cm-2 s'1, 8 MW reactor power, 8.2 cGy/min) for 5,10 or 20 min. The brains were examined histologically 8 h after irradiation. In animals irradiated for 5 to 10 min (41 and 82 cGy-Eq, respectively) lethal damage of cells was found in the external granular layer of the cerebellum and the subependymal layer of the forebrain. Irradiation for 20 min (164 cGy-Eq) caused more extensive destruction of cell populations in these regions and, in addition, dead cells appeared also in the more differentiated postmitotic compartments, namely the deeper layers of the cerebellum, layers II/III of the cerebral cortex and corpus callosum. In the forebrain periventricular layer, the extent of cell damage was declining towards the olfactory bulbs. In intact animals, as well as in those injected only with the 150 p\ phosphate buffered saline, the radiation damage was low and limited only to the most sensitive dividing populations of the cerebellum and the forebrain. The study demonstrates a differentiation-dependent damage of the rat brain cells by alpha particles and presents a simple model for evaluation of the biological effectiveness of slow neutron beams constructed for neutron-capture therapy of tumors.
Cílem tohoto článku je metodologický rozbor předpokladů, které používáme, když přemýšlíme o pojmech jako mysl, myšlení, vědomí, poznávání a zkušenost. V první části ukážeme, za jakých předpokladů má smysl chápat mysl jako proces, který je možno popsat formálním modelem a kde jsou meze modelování. V druhé části se zaměříme na alternativní metodologické přístupy, které umožňují poznávat mysl, resp. zkušenost nikoliv pomocí formálních modelů, ale reflexivním nepojmovým poznáváním, které budeme označovat jako vhled., This article deals with methodological assumptions we use when thinking about such concepts as mind, thinking, consciousness, cognition and experience. The first part describes assumptions under which we can formally model the mind as process and where are the limits of such formal descriptions. The second part describes alternative methodological approaches enabling us to understand mind not by means of formal models, but through reflexive non-conceptual understanding called insight., and Burian J.
The paper reviews neutron sources, chemical compounds and clinical perspectives of the boron neutron-capture therapy of brain tumours. Special attention is paid to the physical characteristics and biological effectiveness of the epithermal neutron beam constructed at the LVR-15 nuclear reactor at Řež near Prague.